We will express recombinant forms of human cytomegalovirus (CMV) glycoprotein B for use in the development of a subunit vaccine against CMV. We will use in vitro mutagenesis and other recombinant DNA techniques to generate two forms of glycoprotein B: 1) an uncleaved gB molecule lacking the C-terminal transmembrane and cytoplasmic domain; 2) a C-terminal gB fragment fused to a heterologous secretory signal sequence. Expression plasmids encoding those constructs will be tested in mammalian cells for secretion and reactivity with CMV neutralizing monoclonal antibodies. Our aim is to develop retains the major gB neutralizing epitopes. Our long- term objectives will involve purification of recombinant forms of gB produced by mammalian cells. This material will be tested in animals for the ability to generate neutralizing antibodies. Those recombinant antigens which elicit a strong neutralizing response will be used to develop a subunit vaccine capable of reducing the serious consequences of CMV disease in neonates and transplant recipients. This vaccine will be initially tested in seronegative transplant recipients. Further clinical trials will also be done in females of child-bearing age at risk for CMV infection, such as parents of children attending daycare centers.